The invention disclose a pressure sieving combination device in seed air sieving equipment. The pressure sieving combination device comprises a fixing base plate; an I-shape sliding groove is formed in one side of the fixing base plate; a nylon block is embedded in the sliding groove; superposed inclined strip holes are correspondingly formed in the middle portions of the sliding groove and the nylon block; a limiting plate perpendicular with the sliding groove is arranged at the middle of the sliding groove; a vertical strip hole is formed in the middle of the limiting plate; a long bolt penetrates through the vertical strip hole and the inclined strip holes to connect an upper slide rail combination and the limiting plate to the two sides of the fixing base plate; a lower slide rail combination is arranged below the upper slide rail combination, and is mounted on the fixing base plate; lateral sides of a sieving frame combination are fixed to the lower slide rail combination; and thebottom of the upper slide rail combination abuts against the top of the lateral edge of the sieving frame combination. Through pushing the sliding groove and arranging the nylon block on one side ofthe fixing plate, the long bolt is pushed to rise or lower by the lateral edges of the inclined strip holes, and therefore position of the upper slide rail combination can be changed, the sieving frame combination can be replaced conveniently.